Winter front mileage?

[gr8shot]

Doing 80mph on the interstate, I had my winterfront on, and noticed my mileage for the 3/4 of a tank I had in the truck settled at a less than usual 16.5 on DIC, (15.1 hand calc'd) Thought it was a little low since there was zero wind. When I stopped to refill, I slid the winter front down and rolled the excess down and opened up the top half of the grill. After I did that, the very next tank of fuel resulted in 18.4mpg on the DIC (17.0 hand calc'd). Exact same conditions for both tanks ~25*F outside, zero wind, heading west on I80/I76 to Denver. Actually there was more hills on the second tank, so it should have been worse I'd think.

Only things I noticed after sliding the winterfront down was that my IAT's dropped from around 100-130*F range down to the same as ambient temp, and that my engine temp went from 195 down to 185. (running a stock/no DPF tune if it matters)

Does it seem a little strange that cooler IAT's and 10* less engine temp result in almost a 2mpg gain? Or did someone slip some Monster diesel additive in my tank? :rofl:

 

[FullSpec]

the fuel blend for winter between stations changes so drastically i only trust one place for my fuel in the winter time, i fueled up in broomfield last week and ended sucking down a 1/2 tank in 120 miles, horrible ( the fuel must have been really thinned out and i did not have an 2stroke oil on me to add in). Becareful where you fuel up. the only thing i can say is consistent mpg gains in the winter is the overall lower average fuel temp in the tank.

 

[DAVe3283]

Yeah, I am with FullSpec, unless you filled up at the same station, you can't attribute the change in mileage to the winter cover.

 

[gr8shot]

Yeah I suppose. I've filled up at both stations quite often when I'm around them. Both run the same brand of fuel (sinclair) so I wouldn't think they'd be much different but I guess I could be wrong. FWIW I got the same mileage, about 17mpg on the way back as well with the winter front rolled down.

 

[FullSpec]

hrmm, well it could very well be the aero, time to go to the wind tunnel!

i always wondered what my gain in mpg would be without the reeferbox in the back, i get a 17mpg overall average (which i have worked hard for) that thing is about as aerodynamic as an apartment complex

 

[Dozerboy]

Probably a fluke IIRC aerodynamically the truck should be better off with the grill covered.

 

[UPS DRVR]

could the fan not running as much with the cover down cause the milage diff just a noob throwing out ideas. I could be way off and this has nothing to do with it.

 

[Colt]

Fan seems to eat 2 mpg. when that kicks into action. You must have been on the balance pt. for that fan but it's good to hear how cooler made that much better mileage even if we read that cooler fuel and air is what gives power and mpg. Guess we could try and get this temp setup for a good average mpg. result. Watch temps more might just be worth a bit of time spent.

 

[FullSpec]

the thing that bugs me about the cover is no cold air for the intercooler. I had to run it on friday because it was so cold, i actually lost mileage, but i think it was from the slower speeds due to all the snow, ice, and retards on the road.